Stabilization of gasoline and the like



Patented Aug. 1, 1944 Jacque C. Morrell, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application May 16, 1938, Serial No. 208,222

7 Claims.

This invention relates to stabilization of gasolines, and more particularly to the prevention of color formation and gum forming substances in gasoline, and also to prevent the reduction in antiknock properties of said gasoline on storage. In my earlier copending application Serial No. 406,515, filed November 11, 1929, I have disclosed the stabilization of cracked gasoline against gum and color formation by the addition thereto of small amounts, from a trace up to 2%, of naphthalene derivatives, including the alkyl derivatives, such as methyl and ethyl naphthalene. The

present application is more particularly directed to motor fuel comprising cracked or gum-forming gasoline containing, as a gum flux or retarder of gum deposition, from 0.2 to 2% of a normallyliquid alkylated naphthalene hydrocarbon having a boiling point above 450 F., specifically methyl and ethyl naphthalene.

It hasbeen observed that when gasolines are stored, particularly cracked gasolines, and especially under the influence of light and oxygen,

chemical changes occur which afiect the color, in-

crease the gum formation, and reduce the antiknock properties. In some cases all of these changes occur simultaneously, while in others they occur independently or in pairs; Although the chemistry of thesechanges is not thoroughly understood, I have discovered that certain compounds act as stabilizing or inhibiting agents and substantially prevent this undesirable chemical change from occurring.

Generally speaking, cracked gasolines are composed of mixtures of hydrocarbons, principal among which are the aromatic, unsaturated, naphthene, and paraffin hydrocarbons. While it has not been definitely proven, it is believed that color and gum formation and reduction in antiknock proper ties upon storage involve changes in the unsaturated compounds, more particularly'in the highly unsaturated compounds such as diolefins, terpenes, and related compounds. Oxidation products of the various hydrocarbons present in the gasolines are apparently-responsible also for the changes noted. I

The formation of color in gasolines is undesirable mainly from a marketing viewpoint, for changes in color are usually accompanied by the formation of gum-like and polymer-like materials which affect not only the sale of the 'gasoline when dispensed from visible bowls, but also the operation of the motor owing to clogging of the gasoline feed lines, interference with the proper operation of the carburetor, and the sticking of valves in the motor. Gum formation is likewise objectionable for the same reasons.

The gum content of a gasoline is measured by a test which involves the gum formation. The

present test is stated in terms of milligrams of gum formed upon the evaporation of a specific volume of the gasoline, namely, 100 cc. The presence of oxygen during evaporation increases the gum formation, but as this condition is one which is present in the use of the gasoline, it has a bear-- ing upon its performance in the 'motor. The so-called gum content of the gasoline will also vary as a function of the material in which it is evaporated, for example, in the presence of copper, the resulting. gum will be very much higher than in glass. These tests have a bearing upon the performance of the gasoline in the motor and .its auxiliary feed system, and the beneficial effects of my invention will beindicated by such tests as well as by actual motor tests.

The antiknock property of a gasoline is among its most important and valuable characteristics.

The higher the antiknockvalueor rating of a gasoline, the more efficient it is as a motor fuel. Knocking in a motor is an index of inefl'icient operation because energy which otherwise would be utilized in the operation of the motor must be dissipated by rapid cooling, and unless this remedy is resorted to, a condition will be set up where auto-ignition occurs, thus interfering with the normal functioning of the motor. It has been observed that the higher the compression pressure or compression ratio of a motor, the greater the tendency for a given fuel to knock, and inasfnuch as the efliciency of a motor increases with compression pressure and compression ratio, it is desirable that a motor fuel possess sufllciently high antiknock properties to avoid knocking. The present tendency is to increas the compression pressure of motors in order to increase their efficiency or mileage per gallon or fuel consumed so that antiknock fuels are at a premium.-

The change in antiknock rating during storage of a motor fuel is particularly embarrassing in that although the antiknock rating of a tank of motor fuel is establishedand found to be satisfactory, there is a complete uncertainty as to its percent, more or less, of the inhibiting or stabilizing agents which are the subject of this invention are added to a gasoline which shows a tendency to depreciate with respect to color, gum,

and antiknockproperties, that such gasolines will practically retain their original condition. I have found that these inhibitors or stabilizers are effective in preventing the changes which take place as a result of storage, exposure to after three days.

light, or oxidation naturally occurring or under accelerated conditions.

I have discovered that naphthalene and its derivatives and homologues when added to motor .fuls, especially crackedgasoline, are capable of accomplishing the stabilizing and inhibiting effects above pointed out, and in the present invention I employ for the purposes set forth naphthalene and its derivatives, such as the naphthols, alpha and beta; the alkyl derivatives of naphthalene, for example, methyl and ethyl naphthalene, naphthylamines, both alpha and beta, tetralene or tetrahydro naphthalene, and other derivatives of naphthalene. I

I am aware that certain of the above compounds possess antiknock properties but the present invention is to be distinguish from the mere addition of antiknock compo s to motor fuels in that my treatment preven sdeterioration of the gasoline upon storage as above described. In my invention, the amountof reagent employed is materially less than that required in motor fuels to. impart antiknock properties thereto. For example, with naphthalene 0.1% will serve effectively to perform the purposes of my invention,

Asexamples of the color stabilizing properties of naphthalene and its derivatives, I may cite as examples the following:

\Starting with a gasoline -of 18 Saybolt color which on exposure to diffused sunlight dropped to 14 color in three days without the. addition of naphthalene or its derivatives, I have found that by the addition of approximately one-tenth percent of naphthalene itself the color of the gasoline under the same conditions of exposure was 19 With beta-naphthol the color was 16 under the same conditions, and with tetra lene or tetrahydrona'phthalene the color was 21 after three days exposure, and it will be observed that not only was there a. stabilizing of the color, but there was actually an improvement with naphthalene and tetralene. I In regard to the stabilization of gums, starting with a gasoline showing 6 mgs. of gum per 100 cc. by the glass dish test, which on exposure for twenty-four hours to sunlight increased to a gum out the use of my reagents dropped as low as zero benzol equivalent from a value of approximately was prevented by the addition of 'small amounts of naphthalene and its derivatives.

It can be appreciated that the present invention is of prime economic importance to the oil refining industry since it assuresa stable product after refining and at the same time avoids a large expenditure in bringing up the antiknock properties of depreciated gasoline by the addition of costly antiknock dopes or hydrocarbons possessing high antiknock properties, such as benzol. These inhibitors are not to be confused with antiknock dopes, because the amount added will give no antiknock properties per se, but simply acts to prevent the loss of antiknock and other desirable properties of the gasoline.

The above examples are given by way of illustration on1y and are not to be'construed as limitations upon the spirit and broad scope of the invention.

I claim:

1. A motor fuel comprising cracked gasoline which contains non-volatile gum that deposits on 2. A motor fuel comprising gasoline containing a non-volatile gum dissolved therein which normally tends to deposit in the cylinders of the motor and containing, as a gum flux, from about 0.2 to 2% of a normally liquid naphthalenehydro- 'carbon having at least one alkyl group containing 2% of a normally liquid methyl naphthalene hydrocarbon having a boiling point above 450 F.

4. A motor fuel comprising gasoline containing a non-volatile gum dissolved therein which normally tends to deposit in the cylinders of the content of 16 mgs., the addition of one-tenth percent by weight of naphthalene showed only 2.5

mgs. of gum after-exposure. with a gasoline showing approximately 13 mgs. of gum, no in--.

crease in gum was shown when beta-naphthol or tetralene were used to the extent of approximately one-tenth percent; whereas a blank sample without the addition of a stabilizer showed a marked increase in gum content. Similar results were obtalned when the'gasoline was subjected to accel-- use of naphthalene and some of its derivatives during the oxidation will show a gum content of approximately one-half that of the gasoline where the stabilizer or inhibitors were not present.

Similar results were shown with regard to the antiknock properties, which in some cases withmotor and containing, as a gum flux, from 0.2 to 2% of a normally liquid ethyl naphthalene hydrocarbon having a boiling point above 450 F.

5. Motor fuel comprising cracked gasoline normally tending to deposit gum-like substances on the valves and other parts of the motor and containing, as a retarder for such gum deposition, from 0.2 to 2% of a normally liquid alkylated naphthalene hydrocarbon having a boiling point above 450 F. I 1

6. Motor fuel comprisingcrackedgasoline normally tending to deposit sum-like substances on the valves and other parts of the motor and containing, as a retarder for such gum deposition, from 0.2 to 2% of a normally liquid naphthalene hydrocarbon having a boiling point above 450F. and having an alkyl group containing at least two carbons atoms attached to the naphthalene '7. Motor fuel comprising cracked gasoline normally tending to deposit gum-like substances on thevalves and otherparts of the motor and containing, as a retarder for such gum deposition, from 0.2 to 2% of a normally liquid ethyl naphthalene hydrocarbon having a boiling point above JACQUE c. MORRELL. 

